Search Results (344)

This study investigates the preparation and characterization of tin micro- and nanoparticles with an emphasis on phase-transformation-induced particle formation and chemical purity. Microparticles were generated through repeated phase transformations between β-Sn (white tin) and α-Sn (gray tin), exploiting the associated volumetric changes to induce fragmentation and particle size reduction. The evolution of particle size distribution was systematically analyzed as a function of transformation cycles. The data were analyzed using the modified Johnson–Mehl–Avrami–Kolmogorov equation, and the saturation particle size corresponds to the grain size of the original tin sheet. The phase transformation was induced homogeneously by α-Sn particles and heterogeneously by InSb, and the results were comparable. The influence of the surrounding atmosphere was studied. The increase in oxygen content during repeated phase transformation was measured. In parallel, tin nanoparticles were synthesized via a solution-based route using ammonium hexachlorostannate as a precursor. The nanoparticles precipitated from this solution at mild temperatures during the β-Sn to α-Sn transformation at 13.2 °C. Both micro- and nanoparticles were characterized in terms of morphology and size distribution. The results provide insight into the relationship between phase transformation and particle size reduction mechanisms, and offer a controllable pathway for the preparation of tin particles across micro- and nanoscale regimes. Full article

The prediction of thin-bedded, favorable sand bodies within the Middle-Lower Jurassic braided river delta–lacustrine succession of Block S (Amu Darya Right Bank) is challenging because of strong spatial heterogeneity, deep burial, and limited seismic resolution near the acoustic basement. To address this, we propose an integrated workflow that combines sedimentological characterization with geologically constrained seismic inversion. The study uses core, grain-size data, wireline logs, and 3D seismic surveys. Core–log–seismic integration first delineates three subfacies and nine numbered microfacies (MF1–MF9), with the delta front dominated by underwater distributary channels (MF1), mouth bars (MF2), and interdistributary bays (MF3). Planar microfacies distribution maps and electrofacies boundaries are then used as geological constraints for reservoir prediction. Steerable pyramid enhancement ($K=4$ scales, $N=6$ orientations) improves channel-reflection continuity, and PDF-regularized stochastic optimization inversion ($\lambda =0.8$) is performed to identify thin sand reservoirs. Sand-ratio and GR cutoffs were validated against 412 core–log contacts in five wells. Discretization sensitivity tests confirm stable inversion under 2 ms and 4 ms sampling. The results show that (1) favorable Type I and Type II reservoirs occur preferentially in MF1 and MF2 (average porosities of 12.7% and 10.1%, respectively); (2) vertically, two sand-rich progradational intervals (Lower Member and late Upper Member) are separated by a transgressive mud-prone middle–early Upper Member; and (3) inversion low-impedance anomalies delineate strip-like and lobate channel–mouth-bar sand belts with thickness up to 14 m, consistent with well control. Fault-controlled graben–horst paleotopography influenced sand fairway distribution. The workflow highlights the value of integrating sedimentary microfacies boundaries as geological constraints in seismic inversion for heterogeneous deep clastic gas reservoirs. Full article

Microspheres recovered from energy sector processes, primarily as by-products of large-scale power generation, represent a valuable aluminosilicate resource with significant application potential. Their effective upgrading is essential to maximize material recovery and support circular economy strategies aimed at reintegrating industrial by-products into high-value applications. However, the heterogeneity of microspheres in terms of grain size distribution, density, and mechanical strength poses a challenge for their efficient processing and standardization. This study presents a refinement method and process line for upgrading microspheres obtained from the energy sector into high-mechanical-strength products. The proposed approach is based on the systematic fractionation of raw material, supported by the detailed characterization of feedstock from different sources and continuous control of key technological parameters. Particular emphasis is placed on optimizing separation processes and final blending strategies to ensure consistent product quality. The developed technology enables the production of microspheres meeting stringent requirements, thereby expanding their applicability in demanding industrial sectors such as drilling engineering. At the same time, the approach contributes to increased resource efficiency by redirecting a significant portion of energy sector by-products back into the economic cycle, in line with circular economy principles. Full article

Surface soil grain-size distribution (GSD) is a fundamental terminal record of aeolian processes and land-surface erodibility. However, a macro-scale understanding of GSD spatial heterogeneity and its quantitative coupling with seasonal atmospheric circulation dynamics in Central Asia remains insufficient. Based on an extensive dataset of 325 surface soil samples across Kazakhstan, Uzbekistan, Kyrgyzstan, and Tajikistan, this study systematically investigates the GSD patterns and their climatic drivers. Our results reveal a pronounced spatial gradient: coarse-textured soils dominate the northwestern and eastern desert plains, whereas fine-grained sediments are sequestered in the southeastern mountain-basin systems. We demonstrate that this heterogeneity is rigorously governed by seasonal wind regimes: the Siberian High directs coarse particle entrainment and transport during spring, while the mid-latitude westerlies and local topographic modulation (e.g., the Tian Shan and Pamir barriers) control the fine-grained sorting continuum. Furthermore, the desiccated Aral Sea bed serves as a distinctive anthropogenic dust source, perturbing regional natural sorting patterns. These findings provide critical empirical constraints for dust emission modeling and underscore the sensitivity of Central Asian land surfaces to shifting atmospheric circulation patterns. Full article

The Late Eocene Huizhou-A sandy conglomeratic system in the Pearl River Mouth Basin presents a highly heterogeneous reservoir system shaped by intense synsedimentary fault activity and variable depositional processes. Utilizing 3D seismic interpretation, well log analysis, and core calibration, this study reconstructs the tectono-sedimentary evolution, facies distribution, and diagenetic modifications controlling reservoir quality. Results show that the best reservoir quality is not confined to proximal fan-delta coarse-grained deposits near steep boundary faults, but occurs mainly in fan-delta front and braided-river-delta deposits, especially braided- and turbidite-channel microfacies. These reservoirs benefit from better sorting, favorable grain size, and higher textural maturity, whereas proximal clastic-flow deposits are poorer due to heterogeneity, poor sorting, and compaction. Reservoir quality is also depth-dependent: upper Enping reservoirs are mainly controlled by maturity, while lower Enping reservoirs are more influenced by grain size. Semi-quantitative analysis identifies the 7–11 km transport-distance zone as the optimal fairway for vertically stacked high-quality reservoirs. This approach not only guides exploration and development in the Huizhou Sag but also offers a transferable predictive model for similar steep slope lacustrine rift basins with comparable tectono-sedimentary settings worldwide. Full article

This study investigates the mechanical performance of a pulsed laser butt-welded IN792 DS joint and its relationship to its microstructure by means of grid nanoindentation. A new ISE-free (rate-derived) hardness parameter (H_R) has been introduced to account for the local bulk elastoplastic behavior of the material in combination with the stable contribution of residual stress, thus overcoming the limitations of the current standard codes. It allows performance comparability between different welding experiments, materials, and joint configurations. It offers an alternate means to mechanically determine the HAZ width when microscopic and metallurgical methods fail to detect it. Moreover, the spectra of two independent indentation parameters have been utilized as an input within an iterative statistical deconvolution scheme to estimate the composition of the relevant phases present within the fused zone. While one parameter spectrum acted as a predictor in the first stage, the second one served as a corrector for the final estimation of the four detected phases, thereby self-validating the iteration procedure with 5% tolerance. The validity of phase estimation was first determined over the entire FZ and then at three levels of the weald seam (top, neck and bottom) for further validation. The results indicate that the γ-matrix and ultrafine fine/hard second phases in the fused zone amounted to 54% and 43% volume fractions, respectively. The associated deconvoluted mechanical performance, expressed in terms of E_IT, H_IT, and H_R, corresponded to approximately 209 ± 4.5, 6.3 ± 0.2, 4.4 ± 0.1 and 224 ± 7.0, 6.7 ± 0.1, and 4.6 ± 0.1 GPa, respectively. A correlation between the estimated phases and the local mechanical performance via the conventional indentation parameter (H_IT and E_IT) and the new H_R parameter in the three relevant regions of the fused zone was discussed while discerning the effect of cooling rate on precipitate size, heterogeneity, porosity, residual stresses, and grain orientation. Further validation studies on different sample geometries, materials and joint configurations are needed to confirm the generality of the proposed methodology. Full article

This industrial-scale study investigates cerium’s effect on inclusions, microstructure, and mechanical properties in Ti-bearing high-strength steel BT700L through comparative trials of two production batches (with/without 0.0035% Ce). Characterization via SEM/EDS, automatic inclusion analysis, and Factsage thermodynamic simulations revealed that Ce addition reduced spherical Al-Mg-Ca-O-S inclusions (from 24 to 7 per 2 mm²; size decreased from 17 μm to 10 μm) while promoting composite inclusions with AlCeO₃-Ca(Mn)S cores and Ce-containing Ti(C)N shells. Although square Ti(C)N inclusion numbers remained stable, their average size increased from 8 μm to 11 μm. Ce addition eliminated banded microstructure and refined grains through heterogeneous nucleation (Ce₂O₃ exhibits low misfit of 4.00% with α-Fe). Mechanically, yield strength increased marginally (<5%) with unchanged tensile strength and reducing elongation. However, −20 °C impact toughness decreased by 22%. This duality—beneficial grain refinement versus detrimental coarsening of angular TiN inclusions acting as stress concentrators—provides critical insights for optimizing Ce addition in industrial Ti-bearing high-strength steel BT700L. Full article

Volcanic ash preserves critical information on eruption dynamics, magma evolution, and fragmentation processes, yet its small size and fragile structure pose challenges for conventional analytical methods. Advances in SEM-based automated mineralogy combined with X-ray mapping (GXMAP) provide high-resolution characterization of ash textures, particle morphology, and mineral assemblages, offering a more robust basis for interpreting pyroclastic deposits. This study applies an integrated GXMAP workflow alongside sieve-based granulometry to the Early Pleistocene trachyandesite to rhyolitic pyroclastic sequences at the Kurtan quarry (Kechut Volcanic Province, Armenia), a key regional stratigraphic marker associated with early human occupation. GXMAP-based granulometry minimizes preparation-induced fragmentation and yields more consistent and reliable grain-size and morphological data for fine ash deposits than dry sieving. The three stratigraphic units at Kurtan display distinct combinations of grain size, mineral assemblages, and particle morphologies, reflecting contrasting magma evolution, fragmentation conditions, and depositional regimes. Shape-parameter fields derived from BSE images reveal clear differences between the highly irregular, concave compound fragments dominating TP-13-1 and the smoother, more compact particles characteristic of TP-13-2 and TP-13-3. Most particles fall within the ductile domain of established shape-morphology diagrams, indicating that ductile deformation of bubble walls was a major component of fragmentation, accompanied by heterogeneous brittle breakage. These results demonstrate the effectiveness of the combined SEM-based automated mineralogy and GXMAP approach for resolving primary fragmentation, sorting characteristics, and depositional processes in fragile pyroclastic deposits. The Kurtan sequence provides new constraints on explosive volcanism in the Lesser Caucasus Mts. region. At the same time, the methodological framework offers broad applicability to tephra studies worldwide and underscores the potential of imaging-based techniques in volcanology. Full article

Brain tumor segmentation from 3D MRI presents significant challenges due to small lesion sizes, ambiguous boundaries, arbitrary spatial distributions, and heterogeneous morphological properties. To tackle these issues, this paper presents a fully automatic 3D brain tumor segmentation network that integrates morphological and anatomical information under a multi-task learning framework for whole tumor, tumor core, and enhanced tumor segmentation. We propose a multimodal feature fusion module to adaptively weight features from four MRI modalities (T1, T1ce, T2, FLAIR), enabling discriminative information integration and helping reduce modality intensity discrepancy and data imbalance. Furthermore, a ConvReXt downsampling module is introduced to preserve fine-grained semantic details by reducing information loss caused by conventional pooling. A dense parallel global attention module is also developed to capture both local details and long-range dependencies, addressing the limited receptive field of standard convolutions. Extensive experiments on the BraTS2020 dataset show that the proposed model obtains average Dice coefficients of 92.54%, 89.21%, and 86.54% for whole tumors, tumor cores, and enhanced tumors. The proposed model achieves competitive performance compared with state-of-the-art methods including nnFormer, validating that it can effectively fuse multimodal and multi-scale features and improve brain tumor segmentation accuracy. Full article

Heterogeneous grain structured design has emerged as an effective strategy to overcome the limitations of mechanical properties in structural materials. Core–shell heterogeneous grain structured materials exhibit a good strength-ductility synergy owing to their continuously networked grain topology. However, controlling the grain size and fraction in core–shell structures through mechanical milling and powder metallurgy remains challenging. Therefore, the effects of grain structure topology on mechanical behavior remain unclear. This study establishes a crystal plastic finite element (CPFE) model of a core–shell structure and discusses the effects of core–shell topological characteristics, i.e., core–shell fraction (S_f = 15% to 65%), the core–shell interface gradient (θ = 63° to 90°), and the coarse grain/ultrafine grain size ratio (CG/UFG = 8/2 to 8/1), on tensile strength and hetero-deformation induced (HDI) hardening. The results indicate that the tensile strength is strongly correlated with the core–shell fraction and CG/UFG size ratio. The tensile strength is enhanced with increasing core–shell fraction and CG/UFG size ratio, which can be attributed to the increased fraction of ultrafine grains and their reduced grain size. The tensile strength increases by approximately 30% when the core–shell fraction increases from 15% to 65%, and increases by approximately 12% when the CG/UFG size ratio changes from 8/2 to 8/1. However, these two parameters exhibit a negligible influence on HDI hardening. In contrast, compared to θ = 63°, the HDI hardening at θ = 90° increases by approximately 20%, thus it indicates the sharp core–shell interface gradient markedly promotes HDI hardening, thereby improving the tensile strength through an increased hardening rate. Collectively, this study provides useful information for the microstructure design of core–shell heterogeneous grain structured materials. Full article

Laser cladding has attracted considerable attention for titanium alloy surface modification owing to its high energy density, rapid cooling rate, and excellent metallurgical bonding capability. To investigate the effect of Nb content on the microstructure and properties of NiTi-based coatings, composite coatings containing 10–40 wt% Nb were fabricated on a titanium alloy substrate via laser cladding. The effects of Nb content on phase constitution, microstructure evolution, mechanical properties, tribological performance, residual stress, and surface topography were systematically characterized using XRD, SEM, EDS, microhardness testing, wear testing, digital image correlation, and atomic force microscopy. The results show that increasing Nb content significantly affected the solidification behavior and phase evolution of the coatings. With increasing Nb addition, the dominant phase gradually evolved from NiTi to a coexistence structure of NbTi₄ and NiTi, while Ti dilution and elemental segregation became increasingly pronounced. The crystallite size increased from 19.63 nm to 25.91 nm, accompanied by intensified dendritic segregation and surface roughening. Among all samples, the coating containing 10 wt% Nb exhibited the best overall performance, characterized by the finest microstructure, the lowest surface roughness, the lowest residual stress, and the best wear resistance. The superior performance of the low-Nb coating was mainly associated with its finer and more homogeneous microstructure, reduced elemental segregation, lower stress concentration, and enhanced grain-boundary strengthening effect. Excessive Nb addition intensified Ti dilution, grain coarsening, residual stress accumulation, and microstructural heterogeneity, thereby degrading the overall coating performance. More importantly, this study reveals that Nb-regulated Ti dilution behavior governs the synergistic evolution of elemental segregation, surface roughening, residual stress accumulation, and tribological degradation during laser cladding. This work provides new insight into the process–structure–property relationship of NiTi-based composite coatings and offers theoretical guidance for the composition optimization and engineering application of high-performance laser-clad coatings on titanium alloys. Full article

Engineered geothermal system (EGS) cross-well flow of 30 L/s producing heat at a rate of Q~20 MW for 30 days was achieved by the UtahForge project in 2024. The cross-well flow doublet measured ℓ~400 m in length at L~100 m vertical offset. A first-order question is how sustainable the doublet’s 20 MW heat extraction is. Where once the answer would be framed in terms of pipe-like cubic-law flow along stress-aligned fault-scale planar heat exchange surfaces, UtahForge flow data rule out this heat exchange picture. The EGS flow data indicate aquifer-like volumetric cross-well flow with heat exchange at the grain scale. More specifically, the EGS flow data indicate no cross-well flow for a dozen hydrofrack attempts, while the 30 L/s flow occurred when the 400 m doublet wells were rendered effectively open to the crustal formation by drilling out all hydrofrack gear. An essential further observation is that the producer well flowed at only 70% of the injector rate: 30% of injected fluid was lost to flow heterogeneity in the cross-well volume. A four-step deconstruction of these observations explicitly characterizes the flow heterogeneous volume: (i) flow stimulation of the cross-well volume, (ii)wellbore-centric flow in/out of cross-well volume along the 400 m open well reach, (iii) heat advection in the cross-well volume, and (iv) sustainability-specific heat conduction into the cross-well volume. EGS stimulation process step (i) is attested by microseismic emissions (Meqs) registered on downhole sensors. Meq size and spatial correlations in turn reflect the flow heterogeneity of the cross-well volume. EGS step (iv), crustal heat conduction sustainability, is approximated by assuming radial heat energy extraction at rate Q/ℓ by a central line-sink of radius R < L/2. The line-sink analytic solution yields heat reservoir sustainability of ~3–10 years. Greater sustainability at Q/ℓ rate requires larger cross-well offsets L. The intimate relation between fluid flow and seismic emissions enables downhole seismic sensor data to image EGS flow stimulation activity. The future of EGS heat extraction depends to a large degree on feasible sizes of cross-well offset L in the flow-heterogeneous crust. Full article

Published laboratory data on soil stabilisation are abundant, yet they remain fragmented across studies and are often difficult to reuse because of inconsistent reporting formats, heterogeneous testing conditions, and incomplete metadata. This article presents a curated experimental dataset compiled from 20 published studies on fine-grained soils, comprising 560 records, including 397 unconfined compressive strength (UCS) results and 163 California Bearing Ratio (CBR) results. The dataset is defined by the inclusion of laboratory studies designed around biopolymer-based two-additive stabilisation frameworks, while intentionally retaining untreated and single-additive comparator records reported within the same experimental programmes. This design is a key distinguishing feature of the dataset because it enables analysis of baseline soil behaviour, isolated additive effects, and combined-additive responses within a traceable study context. Across the included studies, the treatment systems cover a wide range of biopolymer- and lignin-related materials, including xanthan gum, guar gum, chitosan, sodium lignosulfonate, and electrolyte lignin stabiliser, together with complementary additives such as cement, lime, fly ash, ground granulated blast-furnace slag, rice husk ash, glass powder, concrete waste, nano-additives, and natural or synthetic fibres. In addition to UCS and CBR outcomes, the dataset preserves key contextual variables required for meaningful secondary reuse, including soil classification, grain-size fractions, Atterberg limits, compaction properties, curing duration, additive identities and dosages, and source-level traceability. The data are distributed as a structured Excel workbook comprising two cleaned outcome-specific sheets (CBR_clean and UCS_clean) and four supporting documentation sheets (StudyInventory, DataDictionary, VocabularyMap, and QC_Log). Record-level identifiers, DOI-linked source fields, inferred-curing flags, and qualified outcome descriptors are retained to support auditability, selective filtering, and reproducible reuse. The resulting dataset provides a practical foundation for comparative assessment of stabilisation strategies, pavement and subgrade engineering studies, meta-analysis, and machine learning applications in geotechnical engineering. Full article

Hypereutectic Al-Si alloys are used in a number of industries; however, the large size of primary Si grains significantly limits their industrial applications. Grain refinement through the addition of modifiers has become a crucial technical approach to overcome this challenge. Rare earth elements, particularly Ce and Er, are promising modifiers, and they have a synergistic effect on the refining of Si in hypereutectic Al-Si alloys. However, the synergistic mechanism between Ce and Er is rarely reported. Thus, this study aimed to reveal the mechanism underlying the synergistic effect of Ce and Er on refining the grains in hypereutectic Al-25 wt.% Si alloy. The results indicate that the synergistic doping of Ce and Er significantly reduces the size of the primary Si grains. The addition of 0.5 wt.% Ce and 1 wt.% Er to the alloy reduced the primary Si grain size to 428.51 μm, achieving an overall refinement rate of up to 55.1% compared with the alloy without Ce and Er. Microstructural analysis revealed that Ce and Er accumulated around the primary Si crystals, resulting in the formation of complex intermetallic phases. These intermetallic complex phases provided additional nucleation sites for the growth of primary Si, thereby promoting its heterogeneous nucleation and inhibiting grain growth. Furthermore, they reduced the intensity of crystal growth in the direction of the preferred growth orientation of the primary Si, thereby further inhibiting its growth. This study provides essential experimental evidence supporting the synergistic refinement of hypereutectic Al-Si alloys using Ce and Er. Full article

Subsurface rolling contact fatigue (RCF) failure is one of the primary failure modes in properly installed and lubricated rolling bearings. Its actual service life often exhibits significant scatter, posing a formidable challenge to the reliable life prediction and operational safety of bearings. This study establishes a macro-meso-coupled rolling contact fatigue model that accounts for crystalline anisotropy and grain topological structures. This model utilizes Voronoi tessellations and random Euler angles to construct a polycrystalline mesoscopic model, which is subsequently integrated with a macroscopic Hertzian contact finite element analysis to simulate the roller bearing loading cycles and determine the localized stress responses within the material. The results indicate that variations in macroscopic structural and operating parameters primarily affect the overall stress level of the subsurface RCF failure. The relative fatigue life of the bearing exhibits an exceptionally high sensitivity to changes in macroscopic and operating parameters. Specifically, an increase in radial load leads to an exponential decrease in relative life, with the Weibull slope ranging between 1.001 and 1.129, which is broadly consistent with the classical Lundberg–Palmgren experimental value of 1.125. Conversely, the heterogeneity of the mesoscopic crystalline structure strongly influences the statistical variance of localized extreme stresses. The scatter in bearing fatigue life demonstrates a much more pronounced sensitivity to mesostructural alterations; as the grain size increases from 10 μm to 40 μm, the Weibull slope drops from 1.041 to 0.784. This study provides an analytical basis for the reliable life prediction of rolling bearings. Full article